[Mesa-dev] [PATCH] glsl: Remove VS output varyings which are optimized out of the FS

[Ian Romanick]

On 02/12/2013 06:59 PM, Jordan Justen wrote:
> Previously when an input varying was optimized out of the
> FS we would still retain it as an output of the VS.
>
> We now build a hash of live FS input varyings rather
> than looking in the FS symbol table. (The FS symbol table
> will still contain the optimized out varyings.)
>
> Signed-off-by: Jordan Justen <jordan.l.justen at intel.com>
> Cc: Paul Berry <stereotype441 at gmail.com>

Is this a candidate for 9.1?

> ---
>   src/glsl/link_varyings.cpp |   19 ++++++++++++++++++-
>   1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/src/glsl/link_varyings.cpp b/src/glsl/link_varyings.cpp
> index b1317c8..616933d 100644
> --- a/src/glsl/link_varyings.cpp
> +++ b/src/glsl/link_varyings.cpp
> @@ -964,6 +964,8 @@ assign_varying_locations(struct gl_context *ctx,
>      varying_matches matches(ctx->Const.DisableVaryingPacking);
>      hash_table *tfeedback_candidates
>         = hash_table_ctor(0, hash_table_string_hash, hash_table_string_compare);
> +   hash_table *consumer_inputs
> +      = hash_table_ctor(0, hash_table_string_hash, hash_table_string_compare);
>
>      /* Operate in a total of three passes.
>       *
> @@ -976,6 +978,18 @@ assign_varying_locations(struct gl_context *ctx,
>       *    not being inputs.  This lets the optimizer eliminate them.
>       */
>
> +   if (consumer) {
> +      foreach_list(node, consumer->ir) {
> +         ir_variable *const input_var =
> +            ((ir_instruction *) node)->as_variable();
> +
> +         if ((input_var != NULL) && (input_var->mode == ir_var_shader_in)) {
> +            hash_table_insert(consumer_inputs, input_var,
> +                              ralloc_strdup(mem_ctx, input_var->name));
> +         }
> +      }
> +   }
> +
>      foreach_list(node, producer->ir) {
>         ir_variable *const output_var = ((ir_instruction *) node)->as_variable();
>
> @@ -986,7 +1000,7 @@ assign_varying_locations(struct gl_context *ctx,
>         g.process(output_var);
>
>         ir_variable *input_var =
> -	 consumer ? consumer->symbols->get_variable(output_var->name) : NULL;
> +         (ir_variable *) hash_table_find(consumer_inputs, output_var->name);
>
>         if (input_var && input_var->mode != ir_var_shader_in)
>            input_var = NULL;
> @@ -1005,6 +1019,7 @@ assign_varying_locations(struct gl_context *ctx,
>
>         if (matched_candidate == NULL) {
>            hash_table_dtor(tfeedback_candidates);
> +         hash_table_dtor(consumer_inputs);
>            return false;
>         }
>
> @@ -1021,11 +1036,13 @@ assign_varying_locations(struct gl_context *ctx,
>
>         if (!tfeedback_decls[i].assign_location(ctx, prog)) {
>            hash_table_dtor(tfeedback_candidates);
> +         hash_table_dtor(consumer_inputs);
>            return false;
>         }
>      }
>
>      hash_table_dtor(tfeedback_candidates);
> +   hash_table_dtor(consumer_inputs);
>
>      if (ctx->Const.DisableVaryingPacking) {
>         /* Transform feedback code assumes varyings are packed, so if the driver
>